From the early military beginnings of the 1950s, remotely operated underwater vehicles (ROV) have evolved quickly from heavy duty work-class ROVs, used in heavy construction and maintenance tasks, to the latest micro ROVs.
Brute strength payload and tooling power are capabilities well suited to the offshore industry, especially when it comes to moving equipment or setting up a rig, but it is in surveillance and increasingly in delicate recovery and monitoring tasks that offshore ROVs excel.
As well as size and increasingly delicate abilities, important developments in software are also an influential part of the ROV tale and their increased uptake has resulted in incredible extensions of operability, with users now achieving complex subsea missions with just the click of a mouse.
Sitting in the middle of the range is the family of light ROVs, also known as inspection ROVs, which have seen good uptake in the offshore industry due to their ability to perform reconnaissance and light tasks, thus enabling an operator to pick the right tool for the job in hand.
An eye undersea
Saab delivered its first Seaeye Falcon ROV in 2002 with a 14kg payload and launched the DR version of the Falcon in 2006.
The Falcon DR is rated to a 1,000m depth and, according to Saab, is the first ROV in its class to have a distributed intelligence control system, which Saab says is “a multi-drop network that allows up to 128 devices to be connected together on a single RS485 serial network and to be individually controlled by a master processor”.
Another company that is advancing along the light ROV route in its portfolio is Sub-Atlantic. The company’s Mohican inspection-class ROV system has three or six simultaneous video channels transmitted through fibre-optic telemetry and has additional powers sources for the attachment of manipulators and tools, including a high pressure jetting and cleaning skid. Sub-Atlantic’s Super Mohawk is rated to 2,000m.
Sub-Atlantic sales manager Alasdair Murrie commented on whether light ROVs can do more,
“Yes and no,” he says. “With smaller and more accurate sensors like multibeam for survey and inspection and smaller Doppler velocity logs and more advanced control systems such as eyeballs are taking more work off work class. However, if brute strength and tooling power are required or huge payload or bigger stronger manipulators then work class will always be required.”
Piloting the depths
Recent technological advances have enabled a range of ever more sophisticated sensor systems for light ROVs allowing the vehicles to do tasks such as port security applications, structural and vessel hull inspection, diver support, surveillance operations, mine countermeasures and intervention/recovery. However, the more tools and systems the light ROV is carrying the greater the challenge for its control systems.
Sub-Atlantic’s subCAN control system is a PC running Windows LabView with a touchscreen monitor and a hand control for the pilot. The system is simple and compact, yet, says Sub-Atlantic, “includes multiple / expandable digital and analogue channels, diagnostics, fault protection and auto positioning”.
Also in the ROV software business, See-Byte says that its SeeTrack CoPilot software product for ROVs has improved ROV operation right up to heavy work-class ROVs.
“At the core of SeeTrack Copilot are dynamic positioning and real-time monitoring,” says Nicole Irvine, spokesperson for See-Byte. “These features enable the ROV to hold position and heading, to change position, move relative to structures and cruise without diverging from the requested speed and heading, all with a simple mouse click. In achieving this, CoPilot makes highly complex subsea missions attainable for even the most inexperienced of ROV operators.”
Challenging industry resistance
See-Byte has faced challenges in bringing its brand to market, not least being resistance to change.
“It is has been surprisingly challenging to persuade large organisations like the military and oil companies to adapt to the latest advancements in software technology, even when there are proven benefits in doing so,” said Irvine.
While there is merit in the mindset of if it isn’t broken, don’t fix it, times and technology move on.
“Improvements in hardware and software technology is making smaller ROV systems more capable,” said Irvine. “Lighter tethers, lighter frames and more efficient thrusters are some of the hardware improvements that are driving towards smaller systems. But, we firmly believe that the real step change in capability is that afforded by the new software technologies.
“By fusing data from navigation and sonar imaging sensors these systems can now be precisely positioned relative to static and moving structures and can be kept stable even when physically in contact with the infrastructure. With this software light ROVs can carry out survey work and maintain a level of stability never before available.”
For the sharp end of operations to improve, the tools controlled by the operating software has to evolve too, CDL in Aberdeen, Scotland, specialises in subsea positioning systems such as TOGS and MiniSense2 while Tritech International says that it is the industry leader for the provision of tools for the ROV and autonomous underwater vehicle (AUV) markets.
The company says that its Gemini imaging sonar has been used for decommissioning operations in the offshore oil and gas industry, where in relatively shallow water operations, light ROVs can prove especially useful.
Tritech’s latest innovation for the ROV market is the Gemini 720i. “It provides a clear viewing platform in low-visibility water conditions,” said Suzanne Menzies, Tritech’s marketing co-ordinator. “With Gemini 720i, ROV pilots would expect to achieve video-like sonar imagery of the underwater scene ahead so that they can navigate with confidence. Tritech’s Gemini 720i imaging sonar allows for clear, real-time navigation of the ROV, so the pilot can pin-point targets, particularly if the location was unknown.”
The company said that it has also noticed the market changing.
“Demand has followed the upturn in the industry following the global recession,” said Menzies. “As the oil price has begun to stabilise, work has continued in key areas from the North Sea to South America. Following this market boost, oil and gas / subsea service providers have been actively investing in inspection ROVs and industry-standard products so that they are well equipped for the challenges they face.”
Menzies confirmed that due to the trend towards deepwater operations “Gemini 720i will shortly be available in a 4,000m depth rating model”.
Light ROVs are not a replacement for the work-class vehicle’s ability to do the heavy work in subsea operations. However, the light-class ROV is more capable than it was and in a market where one size does not fit all, the light ROV has widened its usability options.